1. Field of the Invention
The present invention relates to electric motors, and more particularly, to systems, methods and computer program products for assessing the health of an electric motor without requiring access to extensive historical asset management and historical sensor data.
2. Background of the Invention
Although electric motors are rugged and reliable electromechanical energy conversion devices, they are subject to failure under mis-operation, severe operating conditions, hostile environments, and aging. The average annual failure rate of large electric machines is estimated to be at least three percent. In industries that require the motor to be operated under hostile conditions and environment, such as mining or pulp and paper industries, the annual failure rate can be much higher. Since motor failure has a potential for substantial financial loss, the demand for motor protection has increased, which has driven many researchers in industry and academia to explore new technologies in condition monitoring of electric machines and electrically driven equipment.
Access to historical repair information allows an understanding of the conditional failure probabilities of motor components. According to industry standards, almost one half of the total failures for electric motors are bearing-related. Additionally, one third or more failures are typically related to the winding insulation and core iron. Taking historical performance, failures and repairs of thousands of electric motors into account, probabilities of electric motor failure can be understood with reference to failure Pareto charts. Pareto charts, as are known to those of skill in the art, include a series of bars whose heights reflect the frequency of a problem. Here, given historical failure and repair information, a Pareto chart illustrates the most likely causes for electric motor failure.
Studies have shown that in most cases there is a general agreement between commercially published data and failures of electric motors. Unfortunately, however, greater variations exist in AC motors greater than 2300V. For instance, whereas bearing failures are more prevalent in induction motors due to the presence of a large population of rolling element bearings, in AC motors greater than 2300V AC stator failures replace bearing failures as the dominant problem.
Manufacturers have shown that continuous monitoring system technology is a proven way to reduce motor failures, lower total equipment ownership costs and estimate time-to-failure acceleration factors. Continuous monitoring methods are known to those of skill in the art. However, these systems cannot provide an immediate assessment on the condition of a motor if, for instance, a customer wishes to establish a maintenance/shared risk agreement with a electric motor provider in terms of residual life estimates.
What is therefore needed are systems or methods to rapidly ascertain a motor's health without requiring continuous monitoring or the accessing historical sensor data.